Study On Groundwater Contaminant Transport Combined With Upscaling Methods

Numerical simulation is one of the main methods for groundwater contaminant transportstudying, and the scale problem is a frontier issue in groundwater numerical simulation due toaquifer heterogeneity. This paper introduces two upscaling methods, hydraulic conductivityupscalling and dual-domian mass transfer model to the numerical simulation of groundwatercontaminant transport, and investigates the disciplines of contaminant transport in heterogeneousaquifer with upscaling methods, aiming to solve the problem of missing small-scale informationin groundwater solute transport under larger scales.A combination of hypothetical model and real example is applied. In the study of thehypothetical model, a heterogeneous hydraulic conductivity field is generated using a Markovchain geostatistical technique. Flow field is simulated by MODFLOW and solute transport issimulated by MT3DMS. The effects of hydraulic conductivity upscaling and dual-domain modelon contaminant transport are analyzed by comparing the shapes of the derived breakthroughcurves, peak contaminants and peak arrival times. Then a generalization of the above studyprocedure to the real example of Hunhe River proluvial fan on Lower Liaohe River Plain isexecuted. The hydraulic conductivity field in the example is generated by parametric inversion.The contaminant transports from river linear sources to ambient area and from point sources torivers are studied. Finally, the impact of difference in aquifer heterogeneity on contaminanttransfer in real subsurface conditions is studied.The results show that (1) grid scale determines aquifer heterogeneity. Moreover, heterogeneityhas a small influence on advection and a large influence on dispersion, and these two proceduresare respectively related to peak arrival time and peak concentration of contaminant transport.(2)Peak concentration derived by dual-domain model (progress upscaling) is less than that ofadvection-dispersion model. An obvious peak is always observed in the breakthrough curves ofadvection-dispersion model, and solute concentration rises and drops rapidly. However,“tailing”is observed in the breakthrough curves of dual-domain model, because solute concentration dropsslowly after reaching the peak value. Therefore, it is better to apply dual-domain model togroundwater solute transport simulation in heterogeneous aquifers.(3) To deal with the aquiferheterogeneity, the traditional method of assigning values by blocks cannot accurately reflects thereality, however, the method of generating the heterogenous aquifer by Kriging interpolation canbe used to get a better simulation result of contaminant transfer.